How Elisa Testing and Flow Cytometry Can Complement Elispot Assays

The ELISPOT technique is among the most powerful tools in an immunology researcher’s arsenal. ELISPOT assays are used to determine the number of cells in a blood sample that produce a particular secretion—for example, specific cytokines, antibodies, or granzymes. ELISPOT assays also exhibit exceptional sensitivity, allowing even individual cells to be detected. Such single-cell resolution is possible because the secretory products are captured around the secreting cells before they can be diluted, degraded, or snatched up by neighboring cells. When you need an accurate readout of low frequency immune responses, the ELISPOT assay is the method of choice.

As powerful as the ELISPOT method is, experienced researchers know that other techniques can be used to complement its results. One such technique is the ELISA assay, which is used to measure the amount of various secretions (antibodies, cytokines, etc) in a blood sample. The supernatant used in an ELISPOT assay can be recycled for use in ELISA testing, allowing other substances to be detected. After a cytokine ELISPOT assay has been used to perform T cell monitoring, for example, ELISA testing can be used to extract additional information on the production of antibodies or other cytokines from the same sample—that is, without requiring the use of additional blood draws. ELISA assays thus allow researchers to squeeze additional information out of a sample with only a modest amount of additional effort.

Flow cytometry can likewise be used to provide additional insight into the mechanics of an immune response. ELISPOT assays are exceptionally sensitive at low-frequency response levels—that is, when very few cells produce the desired secretion. In contrast, flow cytometry works best when dealing with high-frequency responses. This makes it an invaluable tool when the cellular responses are excessively large, i.e. too numerous to count using the ELISPOT method.

The bottom line: The ELISPOT assay is exceptionally sensitive and provides unprecedented single-cell resolution, making it a formidable tool for any immunology researcher. There are times, however, when its effectiveness can be further enhanced by using flow cytometry and the ELISA method. When used in concert, these technologies can provide a more comprehensive view of the subject’s immune response.